DD is planning her 13th birthday celebration.
As a bit of background (a bit long, sorry) when DD started secondary all of her friends went to different schools so she has nobody from her old school in her class. She has taken a while to settle and find friends. At the end of Y7 she thought she was in a friendship group of 4 as well as being on the edges of other groups. She was a little closer to one of the group (A) as she lives nearby and they sometimes walk home together. But the 4 of them hung out together at lunch and breaks and sometimes went out after school. A couple of months ago DD found out that one of the 4, (B), had had a sleepover and excluded DD. Nothing mentioned but pics on FB. This happened three times. DD was hurt but being sensible decided not to make a fuss but drift more towards other groups. She is now closer to other groups and is fine. She still walks home with A occasionally.
So now it's coming up to her birthday and one of the activities she's looking at would limit numbers to 12. She's definitely inviting her new groups and as she went to A and C's parties, she wants to invite them too. So that makes the 12. She wouldn't be able to invite B, who has been excluding her. If she wanted to invite her she'd have to think of something else.
So what to do? I regularly read on MN how it is not on to exclude just one person in a group. However as this girl clearly doesn't think of DD as a friend I'm not convinced she should change her plans just so that she can invite her.
Wise fellow MNetters please advise.